1. Field of the Invention
2. Overview of the Prior Art
In the growing of most plant products, plowing is a necessary and integral operation. The reasons for the plowing and the seasonal times in which plowing is conducted may vary from one farming operation to another. However, one of the principal reasons for plowing is to bury ground stubble and/or undesirable plants after a crop has been harvested and to insure that no undesirable growth, such as weed growth is still present on the surface, so that the surface may be prepared for the planting of a new crop.
In my U.S. Pat. No. 5,063,999, dated Nov. 12, 1991 for "Moldboard Plow Apparatus For Switching Soil Strips From One Furrow To Another", I have provided a unique moldboard plow apparatus which is capable of mixing up soil by removing soil strips from furrows and depositing them in other furrows. While this apparatus is highly effective, there has, nevertheless, been a need for a multi-function tillage apparatus which has several different capabilities.
An efficient tillage tool should produce a seed bed with the top layer of soil, namely, that layer which includes stubble and weeds, turned under. A tillage tool of this type should also have the capability of breaking up large clods of soil and also breaking up hard pan and loosening compacted soil beneath the root zone. A tillage tool of this type should also desirably leave the soil surface flat after tillage for immediate planting or subsequent operations, such as harrowing or furrowing.
Tillage tools of the type described should also be effective in having a minimum drawbar pull and should preferably be relatively low in maintenance and repair. When the tool is disabled for purposes of repair or maintenance, farming operations with that tool are effectively halted.
Another important condition for any type of tillage tool is that it should operate effectively across a wide range of soil conditions. It may be appreciated that soil conditions can vary dramatically from one area to another. Moreover, these conditions will also vary dramatically, depending upon weather conditions and the like. Finally, attachments should be capable of being easily added or removed from the tillage tool to reduce the amount of down time and the amount of expensive labor involved in the addition and removal of such attachments.
In addition to the moldboard plow apparatus which I have provided, as described in the aforesaid U.S. Pat. No. 5,063,999, there are also numerous other moldboard plows. Indeed, moldboard plows have been used for centuries in various forms. A few of the early moldboard plows are described in U.S. Pat. No. 1,320 to Barnaby and in U.S. Pat. No. 114,044 to L. P. Rider. The conventional moldboard plow, as used in early times and as presently used, shears a strip of soil from the ground and then inverts it by rolling it over in a manner somewhat similar to the turning of a page in a book. The moldboards also cause a displacement of the removed strip of soil by a distance approximately equal to one furrow width. In this type of plowing operation, fresh soil is exposed on the upper surface of the inverted strip of soil and weeds and stubble are buried under the deposited strip of soil.
This type of soil movement necessarily causes the first strip of soil to be deposited on previously unplowed soil and also causes the opening of a furrow, or channel, in the ground surface. In farm terminology, this operation is described as the first strip of soil "being thrown onto the land." The second and subsequently plowed strips of soil are also thrown into the open furrows made by the previous plows.
The conventional moldboard plow, however, does suffer from a number of deficiencies. The conventional moldboard plows usually include land sides which are designed to provide a balancing of forces imposed from the sides of the plow apparatus. Further, in conventional moldboard plows, the soil is only thrown in one direction. As a result, the plow has a resultant large reaction force which tends to force the plow shares laterally away from the direction of throw. This inherently creates a large amount of frictional force which tends to resist the movement of the plow shares. It is established that frictional forces of this type can result in as much as fifty percent of the total pulling force required. See, for example, Richey, C. B., et al., Agricultural Engineers Handbook, McGraw-Hill Book Co., Inc., New York 1961 pp. 130-131.
From the foregoing, it can be seen that the friction of the land sides which are provided on most conventional moldboard plows and the friction from side loads results in a substantial amount of wasted energy. In addition to the above, the angular plan form of the conventional moldboard plow causes the overall length to increase with each added plow width. The plow further tends to move sideways if soil conditions do not maintain a constant landside support. Nevertheless, it may be appreciated that the soil conditions can vary dramatically in a single plot, thereby greatly affecting the side forces imposed on the plow share.
Another one of the deficiencies of the conventional moldboard plow is the fact that soil is moved in one direction only, as indicated above. This would result in the entire original surface of the field being moved over to one end, if the field was plowed in the same manner for an extended period of time. In addition, large clods are usually left unbroken, requiring a second tillage operation to break up the large clods and smooth out the soil surface.
Extended use of a land plot without deep tillage on a periodic basis may produce a compacted layer at the plowed depth (often referred to as "plowpan"). In order to overcome this problem and other problems, it would be desirable to have provisions for adding a sub-soiler for tillage below the plow depth.
In addition to moldboard plows, discs are also frequently used as a tillage device. However, discs also suffer from a large number of disadvantages. One of the main deficiencies of a disc is the fact that it wastes more energy per square foot of tilled soil than does a plow. It also has much higher maintenance and repair costs than a plow. In addition, the use of a disc arrangement has much higher initial costs attached for working the same area and depth of soil at the most efficient depth of approximately one-fourth of disc diameter.
Another one of the deficiencies of the disc arrangement is that it does not completely invert the top layer of soil, stubble and weeds in one pass. Indeed, in many cases, two or more passes may be required to achieve this result. The back of the disc blade tends to pack the soil and which is an undesirable drawback from the very use of the tillage tool. Finally, this device is not usually available with a sub-soiler device, such as "ripper teeth."
It is, therefore, desirable to provide a tillage tool in which lateral loads, e.g. side loads, are balanced and in which frictional forces, as a result of the side loads, can be reduced. It is also desirable to provide a multi-function tillage tool in which the length of the tillage section does not increase proportionately with increases of tillage width, such that the tillage tool would be competitive with the widest disc devices. There are numerous other functions which are desirable in a multi-function tillage tool.